The full face wheel for vehicles is made up of a disk and a rim. The disk has a circumferential disk flange for holding the tire bead from its side. The rim has, at its one end opening, a joint opening circumferential end to be joined by welding to the back face of the disk and, at its other end opening, a rim flange portion. Here, it is a common practice to join the disk and the rim, in the state of the joint opening circumferential end of the rim made into contact with a specified position on the back face of the disk, by fillet welding from outside along the circumferential direction.
When the disk and the rim are joined by welding, they must be radially positioned so that their radial centers are in agreement with each other, and high accuracy is required in the radial positioning. If the radial positioning accuracy were low, anti-wobble accuracy of the welded full face wheel would be low, which could result in that the vehicle provided with such wheels cannot exhibit desired driving performance. The disk and the rim are also required to be joined by welding in the state of both components being put together and pressed against each other with relatively great forces. This is to restrict thermal deformation due to weld heat produced during welding and to prevent the anti-wobble accuracy from lowering due to the thermal deformation by pressing together the disk and the rim.
A rim disk assembling device, that makes it possible to radially position the disk and the rim with high accuracy and restrict the thermal deformation, as described above, is described in the Patent Document JP-B-2793001. This rim disk assembling device has a structure in which the hub hole of a disk is fit over a hub hole guide provided on a rotary table, and a rim clamp, capable of contacting the rim as guided with a centering pole provided in the center of the hub hole guide, is pressed against the rim placed on the disk.
The hub hole is fit over the hub hole guide to radially position the disk. Further, by pressing the rim clamp against the rim, to bring the disk and the rim placed on the rotary table into pressed contact state and, at the same time, the outside round taper surface of the rim clamp with its wedge effect radially positions the rim. In this way, it is possible to radially position the rim and the disk with high accuracy and bring the both components into pressed contact state.
With respect to the above described rim disk assembling device, the pressing force for bringing the disk and the rim into pressed contact state becomes a direct load onto the rotary table rotated at the time of welding. In order that the load may not work on the driving motor, transmission members, such as gears, are interposed between the rotary table and the driving motor for rotating the rotary table, and the rotary shaft of the driving motor and the rotary shaft of the rotary table are not disposed on the same axis. As for the transmission member, such as gears, it is a common practice to provide small clearance, the so-called backlash, between meshing gears to transmit rotation smoothly. However, due to this backlash, the rotation of the driving motor is not transmitted accurately to the rotary table at the times of start and stop of rotation. As a result, it is hard to rotate the disk and the rim in a stabilized manner at the time of welding, which causes a limit to stabilizing the weld quality.
Moreover, the pressing force for bringing the disk and the rim into pressed contact state is also applied directly to the bearings and the like supporting the rotary table. As a result, local stress concentration occurs on the bearings due to errors occurring inherently in the manufacture of the disk and the rim. The stress concentration could lower strength and durability of the rotary table and the bearings. Moreover, to alleviate such a problem, the magnitude of the pressing force for bringing the disk and the rim into pressed contact state must be limited. As a result, welding cannot be made under a satisfactorily pressed contact state. Therefore, there is a limit to restricting thermal deformation occurring during welding.